We are entering the final hours of the incredible electoral journey of Christine O'Donnell, and what a journey it's been. Though opinion polls have tightened in recent days, bringing her deficit down from a startling 21%, she is still 10% behind her Democratic rival, Chris Coons – and she will almost certainly be roundly beaten in tomorrow's election. But even in a country that has produced more than its fair share of colourful politicians – remember Sonny Bono or Jesse "the Body" Ventura? – O'Donnell has stood out.

Over the past few weeks this Catholic-turned-evangelical Tea Party favourite has dominated the airwaves and clogged up the blogosphere. We've learnt about her interesting views on masturbation (it's adulterous) and Aids (people with HIV brought it on themselves); heard her fulminate against scientists who have created mice with "fully-functioning human brains"; and discovered that her knowledge of the constitution falls short of the first amendment.

We've also learned far more than we wanted to know about her private life, including her problems with paying the rent on time and, thanks to gossip website Gawker, the state of her pubic hair.

But now the rollercoaster ride is nearing its end. "I'm you," O'Donnell told the people of Delaware in her television adverts, but judging from local opinion surveys most residents of the state are not going to return the compliment by voting for her.

But even if she loses, the memory of Christine O'Donnell's fantastical bid for a Senate seat will endure. It has spoken volumes about the state of America, a country that is now so agitated and irritable that it could throw up such a whimsical candidate for the highest office within the party of Abraham Lincoln.

It has also spoken volumes about the impact on the US political process of the Tea Parties, that groundswell of volatile rightwing anger that in two short years has turned the audacious hope of Barack Obama on its head. You would have thought that Tea Party leaders might be a little sheepish today about having helped to build up a candidate who is almost certain to lose.

Not a bit of it.

"We don't regret endorsing her whatsoever," said Amy Kremer, president of the Tea Party Express, one of the most powerful Tea Party affiliations that backed O'Donnell in her primary run for the Republican nomination with hundreds of thousands of dollars.

Jenny Beth Martin, a leader of the Tea Party Patriots, said she too had no regrets that in that race O'Donnell had defeated Mike Castle, a moderate Republican who most observers believe would have had a far greater chance of taking the seat. "Yes, Mike Castle may have won, but what would have been the point of that if all he did was to vote for higher taxes and bigger government, just like the Democrats?"

The issue is not academic. Should the Republicans storm the country in the elections, as some think they might, they will have a shot at passing the magical number of 50 Senate seats needed to snatch the majority from the Democrats. That holds the prospect of Christine O'Donnell going down in history as the woman who cost the Republicans the Senate.

"The chances of the Republicans getting the numbers that they needed was set back very badly when O'Donnell was nominated," said Ross Baker, an expert on Senate politics at Rutgers University.

You get a better sense of what that means by visiting the Montchanin area of Delaware. This is prime Republican country, populated by wealthy families occupying 17th-century mansions and home to the Du Ponts, one of the most prominent families in America, who still live in the neighbourhood and who own the chemical giant that bears their name.

Locals call this "chateau country" and if the Republicans can't win here then they've got a problem. Yet here is Bruce Rudin, a spine surgeon, standing at the front door of his enormous bare-stone pile, replete with swimming pool and tennis courts, explaining why he's voting Democrat. "I think she's unqualified for the Senate," he said of O'Donnell. "I think she's a buffoon and an embarrassment for Delaware."

And here's Paddy Vattilana, a lifelong Republican, who has yet to decide but has serious doubts about O'Donnell. The mother of two small children, she doesn't read the papers or watch TV news, but has gained the impression none the less that O'Donnell is crazy. "She comes across as really strange and a bit of an idiot."

And lastly listen to Becky Terhune, another firm Republican, who flies an American flag over her huge limestone property, where she lives with her four dogs. She voted for O'Donnell in the primary and though she still likes her policies – her religious convictions, her determination to vote against higher taxes – she has begun to wonder if she made a mistake.

"It's on my mind. Maybe I should have backed Mike Castle, he'd have had a better shot."

O'Donnell herself has blamed her poor performance since taking the Republican nomination on the relentlessly bad press that has been flung at her.

"They call you names, they try to make up stories," she said of the so-called "lamestream media" at a rally yesterday organised by the Tea Party Express.

O'Donnell is partly right about her adverse media coverage. Ginger Gibson, a reporter on the local paper, the News Journal, who has been on the O'Donnell beat, says there is a gap between reality and media representation. "She's been portrayed by some as stupid and unintelligent. But she strikes me as a smart woman, incredibly charismatic, aggressive about her core beliefs."

But rough handling at the hands of the media elites tells only half the story. The other half, that O'Donnell pointedly does not mention, is that she was created by the media in the first place.

"I'm responsible for her," declared Bill Maher, the liberal TV pundit, last week. He had a point. It was the exposure he gave O'Donnell on his show Politically Incorrect that first elevated her to national prominence. And it was his airing of a video clip of her talking about her youthful dabbling with witchcraft that began to tear her down.

Those who live by the media die by the media. What a fitting narrative for this most postmodern of elections, where television pundits have supplanted politicians in the national debate. This is the battle of Sarah Palin (Fox News) and Glenn Beck (Fox News) against the mighty Jon Stewart (Comedy Central).